The invention relates generally to apparatus for use in treating proliferative tissue disorders, and more particularly to an apparatus for the treatment of such disorders in the body by the application of radiation, RF energy and combinations thereof.
Malignant tumors are often treated by surgical resection of the tumor to remove as much of the tumor as possible. Infiltration of the tumor cells into normal tissue surrounding the tumor, however, can limit the therapeutic value of surgical resection because the infiltration can be difficult or impossible to treat surgically. Radiation therapy can be used to supplement surgical resection by targeting the residual tumor margin after resection, with the goal of reducing its size or stabilizing it. Radiation therapy can be administered through one of several methods, or a combination of methods, including permanent or temporary interstitial brachytherapy. The term “brachytherapy,” as used herein refers to radiation therapy delivered by a spatially confined radioactive material inserted into the body at or near a tumor or other proliferative tissue disease site.
However, as is well known, the spacing between the radiotherapeutic source and the surrounding tissue is of interest because the radiation dose delivered by a radioactive source is inversely proportional to the square of the distance between the radiotherapeutic source and the tissue. Ideally, the radiotherapeutic source would be placed with respect to the tumor margin so that all of the margin receives the same dosage, i.e. that the tumor margin is disposed on an isodose surface generated by the radiotherapeutic source. A common geometry for an isodose surface would be a sphere. For a radiotherapeutic source with such an isodose surface geometry, the source would therefore be placed so that it is at the center of a sphere defined by the tumor margin. This would enable delivery of an effective tumor dose while minimizing damage to the surrounding normal tissue. This goal entails two requirements-matching the margin tissue geometry to the isodose surface geometry of the radiotherapeutic source and positioning the source accurately with respect to the margin tissue. The first requirement can be difficult to achieve when radiotherapeutic treatments are applied to soft tissue. Even if excision of the tumor produced a spherical post-surgical cavity, the soft tissue surrounding the cavity will have a tendency to slump, or deform. Portions of the unsupported soft tissue may deform towards or away from the radiotherapeutic source. Deviations of the tumor margin from the source's isodose surface will produce areas that are overdosed (and thus healthy tissue can suffer radionecrosis) and areas that are under dosed. Accordingly, improvements are needed not only to ensure the accurate placement of a radiotherapeutic source but also to maintain the tissue margin in a desired geometry during radiotherapy.
Situations arise where a surgeon may determine that a combination of radiotherapy and ablation treatment for a particular recision cavity is advisable. Because of the limitations of existing medical systems, this treatment regime may entail use of an ablation device followed by the use of a second different radiotherapy device. Accordingly, a need exists to provide a unitary treatment system capable of performing both radiotherapy and ablation treatment.
A need remains in radiotherapeutics for instruments providing more accurate radiotherapeutic source placement while improving support of the surrounding tissue. In addition, a need exists for such instruments that may also perform ablation treatments.